I'd guess that, much like ducted, you'll want to consider noise and CFM, though the air will be drawn in to filter, not to expel outside. I didn't see much information in a quick google search about different kinds of charcoal filters, but this video does mention a grease filter and a charcoal filter as separate items. I suppose a bigger charcoal filter would do a better job of taking out odor. https://www.youtube.com/watch?v=zekrgdtty5s

It really will be difficult to keep anything clean above....even sprayable oil on a muffin pan is something I take over to my cooktop area so that my hood will suck it up rather than it get all over my lights above my island. You could always try to get some lights that hang over the areas NEXT TO the cooktop, but if there is any way you can swing buying/installing a hood above the island, that would be the way to go...you can even include pendants if you still want to and the hood can be a more streamlined one.

Your design is very much driven by wishful thinking. I understand. I've been there before. You'd really want it to work this way, and it's frustrating that nobody makes the appliances you want. A downdraft hood is close to useless, with one noteworthy exception, all recirculating hoods are no more than expensive white-noise machines, and even if you could fit in that place, a wall oven really doesn't work well under a countertop let alone under a cooktop. Pretty much the only thing you have going for you is the induction cooktop. That's a solid choice. I suggest you go back to the drawing board and pick a more conventional set up. A induction cooktop, a vent-a-hood recirculating island hood, and a wall oven at countertop level should result in a much more functional kitchen.

I'm not aware of a truly optimal recirculation system, although I'm sure that theoretically some complex of filters could be arranged to nearly perfectly remove effluent from the captured cooking plumes. On the basis of reports here, the Vent-a-Hood ARS seems to be satisfactory, if not optimal (in the sense of effluent removal without regard to cost). Broan/Best have recirculating products, but no reports have been posted here. In general, you want a hood that overlaps the cooking plumes, which requires overlapping the cooktop, and sufficient velocity into the baffle space to ensure containment of the plumes by entraining them into the air moving into the baffle slots. Ejection outside is the best means of further filtering. (For gentle, low plume velocity cooking, mesh filtering can work (with outside ducting) but still requires a larger than cooktop hood.) So, if you didn't already have a hood, then you could go through the simple process I've outlined dozens of times to establish hood size, desired CFM, rated CFM, etc. Then, try to find a recirculating hood that accomplishes that and also performs decent filtering of odor, grease, and other effluent. I don't think the consensus here supports recirculating gas cooktop plumes due to the difficulty of removing all the harmful trace compounds in the combustion products. Induction cooktop filtering might be OK. Opening windows to dilute any contaminants escaping the filtering is also useful, except in highly polluted cities. In any case, there are many factors that mitigate against striving for optimality of performance, including cost, space, and aesthetics, so I'm not going to be fanatically strict about what YOU should do.